Verifying formulas [closed]

I'm trying to Verify that sin(a + b) = sin(a) cos(b) + sin(b) cos(a) with mathematica, but I don't know how to. I've been given a suggestion to use Simplify, but I don't know where/how.

I just started with Mathematica so forgive me if this has a really simple solution. I've searched around but I haven't found anything.

• TrigExpand[Sin[a + b]]. Also FullSimplify[Cos[b] Sin[a] + Cos[a] Sin[b]]
– Moo
Nov 2 '18 at 16:58
• Thank you so much!
– wznd
Nov 2 '18 at 17:59

There's a nifty little function called TrigExpand.
Sin[a + b] // TrigExpand